VT50/OM Rev-A
13
APPENDIX A
Calculation of Safe Personal Distance From Antenna
The Maximum Permissible Exposure (MPE) limit according to FCC 1.1310 is as follows:
Frequency
Limit
30-1500
MHz
F/150
W/m
2
(where F is frequency in MHz)
1500 MHz – 100 GHz
10 W/m
2
For VT50 Upper L-band, S-band, and C-band transmitters (all greater than 1500 MHz),
the MPE is 10 W/m
2
.
For VT50 Lower L-band transmitters, the operating frequency range is 1300-1600 MHz
resulting in a MPE of 8.67 W/m
2
(the lowest MPE in the 1300-1600 MHz range occurs at
1300 MHz and is 1300/150 W/m
2
).
For VT50 UHF transmitters, the operating frequency range is 340-400 MHz resulting in a
MPE of 2.27 W/m
2
(the lowest MPE in the 340-400 MHz range occurs at 340 MHz and
is 340/150 W/m
2
).
Using the formula for the Power Density S = EIRP/ 4
π
D
2
, the distance D, where the
Maximum Permissible Exposure (MPE) satisfies the FCC 1.1310 limit (S=MPE) for
General Population/Uncontrolled Exposure, can be calculated as:
D
≥
√
(EIRP/ 4
π
S) (meters)
where S is the MPE and EIRP is the Effective Isotropic Radiated Power, calculated as:
EIRP = 10
(G/10)
P (Watts)
where G is the logarithmic antenna gain in dBi and P is the transmitter power in Watts.
The resulting safe personal distance calculation is:
D
≥
√
(10
(G/10)
P/ 4
π
S) (meters).
